The present invention relates to a process for producing a gas diffusion electrode and an electrochemical device including same.
Fossil fuel, such as gasoline and gas oil, has been a major energy source for automobiles and power generation since the Industrial Revolution. It has greatly contributed to the improvement of living standards and the development of industry. On the other hand, its enormous consumption is endangering the global environment and draining its resources, which raises concerns and questions regarding its supply over the long-term.
However, hydrogen has been regarded as a substitute for fossil fuel. In this regard, hydrogen can provide a clean, inexhaustible energy source for several reasons. It is a constituent of water and thus can be found in ample supply. It also contains a large amount of chemical energy per unit mass. Further, in use, it is a relatively clean source of energy and does not produce off-gases that can be detrimental to the environment as compared to typical energy sources. It does not emit noxious substances and greenhouse gas.
An apparatus to generate electric energy from hydrogen is continually being research and investigated. In general, the use of hydrogen as an energy source is expected to find use in large-scale power plants, on-site home power plants, as a power source for automobiles or the like.
For example, a fuel cell is generally known to generate electric energy from hydrogen or reaction thereof. The fuel cell generally includes a hydrogen electrode which is fed with hydrogen and an oxygen electrode which is fed with oxygen. On the hydrogen electrode, hydrogen dissociates into protons and electrons by catalysis. Electrons are collected by the current collector of the hydrogen electrode, and protons are transferred to the oxygen electrode. Electrons collected by the hydrogen electrode are transferred to the oxygen electrode through a load mechanism. On the oxygen electrode, oxygen combines by catalysis with protons and electrons transferred from the hydrogen electrode, thereby forming water. In this way there occurs an electromotive force across the hydrogen electrode and the oxygen electrode, which causes an electric current to flow through the load.
As mentioned above, for the fuel cell generating electric energy from hydrogen to create an electromotive force across the hydrogen electrode and the oxygen electrode, it requires that hydrogen should dissociate into protons and electrons on the hydrogen electrode and oxygen should react with protons and electrons to give rise to water on the oxygen electrode. Therefore, the hydrogen electrode may need a catalyst layer to facilitate the dissociation of hydrogen into protons and electrons and the oxygen electrode may require a catalyst layer to facilitate the reaction of oxygen with protons and electrons. Thus, a need exists to form a catalyst layer on the oxygen electrode and/or hydrogen electrode, for example, on the base. However, typical catalysts are materials made of chemically inert substances, and consequently it is difficult and expensive to form a catalyst layer on the oxygen electrode and/or hydrogen electrode.